With conventional electric machines, the cross-section of the induction part teeth--as seen in a section parallel to a plane along the air gap--is at least substantially constant across the height of each tooth, i.e. progressively from the tooth tip adjacent the air gap to the tooth base. This conventional design is not optimum with respect to the magnetic flux conditions in the teeth of the induction part. For, when progressing from the tip to the base of a tooth, an increasing number of windings of the coils located in the grooves participate in the production of magnetic stray flux from tooth to tooth across the groove located therebetween, so that the magnetic flux density is considerably higher at the base or root of the tooth than at the tip of the tooth. Consequently, the tip of the tooth is magnetically not fully utilized, whereas the base of the tooth sets the limit of magnetic utilization.
It is the object of the invention to provide an electric machine of the type indicated at the outset, in which the magnetic flux density utilization of the teeth of the induction part is improved.